QAbstractItemModel::reset() and QAbstractItemModel::createIndex

QAbstractItemModel::reset -
The deprecated function emitted two signals, namely modelAboutToBeReset and
modelReset. Using beginResetModel and endResetModel to emit these signals
instead.

QAbstractItemModel::createIndex -
Ambiguity when compiling with gcc.
When the last parameter is either NULL or 0, GCC fails to resolve
which path to follow. Use the default value (void* ptr = 0) provided in the
function declaration.

Change-Id: I6df26e314bbff6522dab8cd48d328b8b065d91b8